Bus and truck drivers represent a large segment of the US population which has historically had a high rate of musculoskeletal disorders, and research has generally shown that there is an association between exposure to Whole Body Vibration (WBV) and low back disorders. Impulsive WBV exposures have recently been recognized as a risk factor for low back injury, and guidelines for measurement and assessment of these exposures are now available. We hypothesize that bus drivers have WBV exposures that exceed the allowable time weighted average (TWA) and impulsive threshold levels recommended by ISO, and may be at risk of adverse health effects as a result of these exposures. Tri- axial WBV exposures will be measured and characterized by simultaneously collecting traditional TWA and raw, continuous impulsive WBV exposure data. Using a repeated measures design with bus drivers driving on a test route with both city and highway components, various components of variability and potential exposures determinants related to the bus, bus seat, the bus driver, and the route will also be identified. Global Positioning System (GPS) data will also be collected and integrated with the WBV exposure data to facilitate the identification of location, velocity and type of road associated with high average TWA and impulsive WBV exposures. This information may lead to administrative controls (alter speed and/or route of bus, systematically vary type of routes) and/or engineering controls (identify and trigger the need for street repair) to reduce WBV exposures. PUBLIC HEALTH RELEVANCE: Relevance to Public Health: According to data collected by both Washington State and the United States Bureau of Labor Statistics, the transportation industry represents a large segment of the US population which has historically had a high rate of musculoskeletal disorders. Research has generally shown that there is an association between exposure to whole body vibration and low back disorders. Impulsive exposures have recently been recognized as a risk factor and there are now guidelines for the measurement and assessment of impulsive exposures;however, the magnitude of these impulsive exposures and associated health risks, especially in combination with traditional time-weighted average exposures, is unknown in this large group of workers.